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How to Measure: 4ft, 5ft, or 6ft Fume Hoods for Your Lab Layout
You wouldn’t believe how many times I’ve seen a pristine, $3,000 fume hood sitting in a hallway because it physically wouldn’t fit through the lab door. It happens more often than anyone admits.
Labs often order hoods based on the catalog specs alone. But in the real world, “fitting” isn’t just about wall space. It’s about airflow dynamics, elbow room, and whether your team can actually work without bumping into each other.
The three standard widths—4ft, 5ft, and 6ft—exist for a reason. They aren’t just arbitrary cuts of steel. A 4ft hood might save you $500 upfront, but if your chemists are fighting for sash space, you’ll lose that money in a week of lost productivity.
This isn’t just a product catalog. This is the “measure-twice-cut-once” guide I wish my clients read before they called me. We’ll look at the actual math, the hidden installation traps, and the honest pros and cons of Deiiang™’s 4ft, 5ft, and 6ft models.
Understanding 4ft, 5ft and 6ft Fume Hoods
First, let’s talk about the “Feet vs. Metric” confusion. In the US, we say “4-foot hood,” but manufacturing—including ours at Deiiang™—is almost exclusively metric. This matters when you have tight clearances.
Converting Between Feet and Millimeters
Here is the translation that actually lands on the spec sheet:
- 4 feet is nominally 1200mm (Standard)
- 5 feet is nominally 1500mm (Standard)
- 6 feet is nominally 1800mm (Standard)
Expert Tip: Don’t rely on the “1219mm” direct conversion. If you have exactly 48 inches of space between two cabinets, a 1200mm hood fits. A 1220mm one won’t. Always ask for the “External Dimensions” drawing before you drill any holes.
The three standard widths visualized.
Typical External and Internal Dimensions (Deiiang™ Specs)
The most common complaint I hear? “It looked bigger in the brochure.” You need to separate the footprint (external) from the workspace (internal). Side walls and airfoils eat up space.
| Product Type | External Dimensions (L×W×H) mm | Internal Work Space (L×W×H) mm | The “Gotcha” Details |
|---|---|---|---|
| General / PP / Stainless / Explosion-proof | 1200/1500/1800 × 850 × 2350 or 1500mm H (Benchtop) | Varies by model Approx. (L-240) × 530 × 700 | Standard depth is 850mm. If your door is 800mm wide, this unit will not fit unless disassembled. |
| Walk-In Fume Hoods | 1200/1500/1800 × 850 × 2350 | 960/1260/1560 × 530 × 1720 | You lose width to the double-wall structure. Ensure your large apparatus fits the internal width. |
| Ductless Fumehoods | 1000/1200/1500 × 650 × 1100/1900 | 920/1120/1420 × 600 × 700 | Much slimmer (650mm). Great for retrofits but lacks the depth for complex setups. |
| Benchtop Fume Hoods | 1200/1500/1800 × 850 × 1500 | Similar to General series | Check your existing bench depth. A standard 750mm bench is too shallow for an 850mm hood. |
Pro Tip: You lose roughly 240mm of width to the control panels and sash tracks. So, a 6ft (1800mm) hood effectively gives you a 1560mm bench. Plan your hotplates accordingly.
4ft vs 5ft vs 6ft: Which Size Fits Your Work and Team?
Don’t just buy the biggest one you can afford. An empty hood is just an expensive air conditioner sucking money out of your HVAC budget. Let’s find the right tool for the job.
4ft (1200mm) Fume Hoods: The “Solo Pilot”
The 4-footer is compact, but it’s tight. It is designed for one person doing one thing. If you try to cram a rotovap, a pump, and a waste container in here, you’re going to create turbulence and compromise safety.
Deiiang™ Pricing & Reality:
This is your entry-level workhorse. A Deiiang™ General-01 (1200mm) starts around $634. Need to handle aggressive acids? The Polypropylene (PP-01) version is $710.
Ideal for:
- Individual QC testing stations
- Teaching labs (where student density is high)
- Spaces with structural columns limiting wall width
- Low-volume solvent dispensing
5ft (1500mm) Fume Hoods: The Universal Standard
If you are unsure, buy the 5ft hood. It is the most versatile size we sell. It balances bench space with energy consumption perfectly.
The 5ft fume hood (1500mm) adds just 300mm over the 4ft, but that extra foot is where you put your notebook, your samples, or that extra stir plate. It transforms the hood from “cramped” to “comfortable.”
Deiiang™ Pricing & Reality:
You get 25% more space for a fraction of the cost increase. The Deiiang™ General-04 (1500mm) is $824. If you need stainless steel for cleanroom compliance, the Stainless-04 is around $1,965.
Ideal for:
- General organic synthesis
- Setups with one major instrument + workspace
- Labs that need flexibility for changing projects
- Two people working briefly side-by-side
6ft (1800mm) Fume Hoods: The Power User
This is for the heavy lifters. If your hood is your primary “office,” you need 6 feet. This size allows for permanent setups—like a distillation train on the left and a reaction station on the right—without constant dismantling.
The 6ft Powerhouse
Deiiang™ Pricing & Reality:
The Deiiang™ General-07 runs about $1,077. Our Explosion-proof models (essential for heavy solvent use) start around $1,260. Yes, it costs more, but it’s cheaper than buying two 4ft hoods.
Ideal for:
- High-throughput synthesis labs
- Permanent housing of large equipment (GC-MS, ovens)
- Complex multi-stage filtration setups
- Teams of 2-3 researchers working simultaneously
Basically: If you need less than 4ft of linear space, get the 4ft hood. If you need more than 5ft, jump straight to the 6ft.
How to Measure a Fume Hood (Before You Order)
I can’t tell you how many panic calls I get on delivery day because the hood is 850mm deep and the lab door is only 800mm wide. Don’t be that guy.
Measuring the Fume Hood Itself
When looking at Deiiang™ specs (or any brand), check these three numbers:
The “Will It Fit” Checklist
- External Depth (The Door Killer): Deiiang™ hoods are 850mm deep. Standard office doors are often 800-820mm. Measure your door’s clear opening width.
- Total Height: Our standard is 2350mm. Do you have a drop ceiling? You need space above for the duct collar.
- Sash Height: When the sash is fully raised, does it hit your light fixtures?
- Exhaust Collar: Usually a 250mm diameter circle on top. Is your building’s HVAC ductwork nearby?
Don’t forget to account for door handles and hinges!
Measuring Your Lab for the Install
It’s not just about the final spot. It’s about the journey from the loading dock to the wall.
The Delivery Route Audit
1. The Elevator Test:
Can an 1800mm (6ft) crate fit in your service elevator? If not, you might need two 4ft hoods instead of one 6ft hood simply because of logistics.
2. The Turning Radius:
Corners are the enemy. A long fume hood crate acts like a sofa in a narrow hallway. Measure your corridor turns.
3. The Final Location:
- Wall Space: A 1800mm hood needs 1800mm + 100mm wiggle room.
- Aisle Width: NFPA 45 recommends good clearance. Don’t block the fire exit path.
- Service Points: Are the gas/water/electric lines already in the wall? Moving plumbing is expensive; moving a hood on a drawing is free.
Fume Hood Lab Layout: Where and How to Place Units
Placing a fume hood isn’t like placing a refrigerator. Air currents matter. Safety matters.
Basic Layout Principles
Here are the rules we follow when designing layouts for clients:
The “Do Not” List
- No Doorways: Never place a hood right next to the lab door. People walking by create turbulence that can pull fumes out of the hood.
- No High Traffic Areas: Keep hoods away from main aisles.
- Maintenance Access: You need at least 300mm on the side (or access from the front panel) to fix electrical issues later.
- Eyewash Station: Must be within 10 seconds (approx. 55 feet) of the hood, but not inside the splash zone.
Keep aisles clear (min 1200mm) for safety.
Example Layouts: Real World Combinations
Here is how we mix and match Deiiang™ sizes to solve specific problems.
The “Teaching Lab” (Max Capacity)
Room: 6m × 4m
Goal: Fit as many students as possible.
Solution: Two Deiiang™ General-01 (4ft/1200mm) hoods.
Why: 4ft hoods separate the students, reducing chatter and preventing one student’s accident from affecting the other.
Cost Estimate: ~$1,268 (Hoods only)
The “Mixed Use” Lab
Room: 8m × 6m
Goal: One heavy organic synthesis + one acid digester.
Solution: One Deiiang™ General-07 (6ft/1800mm) + One PP-01 (4ft/1200mm).
Why: Dedicate the large hood to complex setups. Keep the small, acid-resistant PP hood strictly for corrosives.
Cost Estimate: ~$1,787 (Hoods only)
The “Production” Lab
Room: 12m × 8m
Goal: High volume, dangerous solvents.
Solution: Two Explosion-proof-07 (6ft/1800mm).
Why: When dealing with volatiles, you need space and airflow. Don’t skimp here.
Cost Estimate: ~$5,071+ (Safety first)
Don’t Forget Walk-Ins and Benchtops
Sometimes standard cabinets don’t work.
Walk-In Hoods
These are basically small rooms. If you have a 50L drum or a floor-standing reactor, you need a Deiiang™ Walk-In. Warning: These take up huge floor space and require serious makeup air.
Benchtop Hoods
These sit on your existing tables. The Trap: Most lab benches are 750mm deep. Deiiang™ Benchtop hoods are 850mm deep. You will have 100mm hanging off the edge unless you buy a deeper bench. Check the load capacity (needs to hold 300kg+).
From the Field: Real Problems We Solved
These are actual scenarios I’ve dealt with recently.
Scenario 1: The “Narrow Room” Nightmare
The Problem: A university had a long, narrow prep room (4 meters wide). They wanted maximum hood space but only had one usable wall because of windows.
The Fix: We used the vertical space. Instead of floor-mounted units that blocked the aisle, we installed two Deiiang™ General-10 Benchtop units (1200mm each) on existing cabinetry. Because they are only 1500mm high, they fit under the window line.
Total Cost: ~$1,066. The client saved thousands on renovation costs.
Scenario 2: The “Split Personality” Lab
The Problem: A startup lab needed to do organic chemistry (solvents) AND acid digestion. They had budget for two hoods but limited space.
The Fix: We split the difference. We installed a 6ft Explosion-Proof hood ($1,260) for the solvents because that equipment is bulky. For the acids, we used a smaller 5ft Polypropylene hood ($963).
Why: Putting acids in a metal hood destroys it. Putting solvents in a plastic hood can be a fire risk. Segregating them by hood type and size optimized their workflow and safety.
Scenario 3: The “Rented Office” Retrofit
The Problem: A cosmetics testing lab rented an office space. The landlord said “No holes in the roof.” They needed a hood immediately.
The Fix: Ductless was the only option. We dropped in a Deiiang™ Ductless Fumehood-04. It’s only 1000mm wide and 650mm deep, fitting on a standard office desk.
Result: Plug and play. No construction crew needed. Cost was slightly higher for the unit ($2,003), but installation cost was zero.
Final Thoughts: Don’t Guess, Measure.
Choosing between a 4ft, 5ft, or 6ft fume hood isn’t just about budget. It’s about workflow.
If you take one thing away from this guide, let it be this: **Measure the path from the delivery truck to the final location.** I’d rather you buy a smaller 4ft hood that fits safely than a 6ft hood that sits in the hallway because the door was 2 inches too narrow.
Deiiang™’s modular sizes (1200mm, 1500mm, 1800mm) are designed to fit standard lab grids, but every building is different.
Your Next Steps
- Define the Process: Acid? Solvents? Heat? This dictates the material.
- Measure the Equipment: Layout your actual instruments on a table. Measure the total length.
- Check the Building: Door widths, elevator height, ceiling clearance.
- Consult the Spec Sheet: Look at the Exact Millimeter dimensions of the Deiiang™ model you want.
Need help double-checking your numbers? That’s what we’re here for.
References & Standards
- • OSHA 29 CFR 1910.1450 – Occupational Exposure to Hazardous Chemicals in Laboratories
- • SEFA 1.2-2020: Laboratory Fume Hoods
- • NFPA 45: Standard on Fire Protection for Laboratories Using Chemicals
- • ISO 14175:2021 – Laboratory fume hoods
- • Deiiang™ Product Technical Data Sheets
Disclaimer: Pricing and specifications are based on 2026 data and subject to change. Always consult with a qualified safety officer and engineer before finalizing lab designs.
